The moat and the chain

The bonobos at the San Diego Zoo used to live in a grotto-type enclosure separated from the public by a 2- meter-deep dry moat. The moat was accessible to the apes by a chain hanging down into it; they could freely descend and climb up again. In Peacemaking among Primates, I described a situation repeatedly observed if the dominant male, Vernon, disappeared into the moat. A younger male, Kalind, would quickly pull up the chain and look down at Vernon with an open-mouthed play face - the ape equivalent of laughing - while slapping the side of the moat. On several occasions the only other adult, Loretta, rushed to the scene to "rescue" her mate by dropping the chain back down and standing guard until Vernon had gotten out. Both Kalind and Loretta seemed to know what purpose the chain served for someone at the bottom of the moat and acted accordingly - the one by teasing, the other by assisting.

Tired of the tire problem

The Arnhem chimpanzees spend the winters indoors. Each morning, after cleaning the hall and before releasing the colony, the keeper hoses out all the rubber tires in the enclosure and hangs them one by one on a horizontal log extending from the climbing frame. One day Krom was interested in a tire in which the water had been retained. Unfortunately, this particular tire was at the end of the row, with six or more heavy tires hanging in front of it. Krom pulled and pulled at the one she wanted but could not move it off the log. She pushed the tire backward, but there it hit -the climbing frame and could not be removed either. Krom worked in vain on this problem for over ten minutes, ignored by everyone except Otto Adang, my successor in Arnhem, and Jakie, a seven- year old male chimpanzee to whom Krom used to be the "aunt" (a caretaker other than the mother) when he was younger.

Immediately after Krom gave up and walked away from the scene, Jakie approached. Without hesitation he pushed the tires off the log one by one, as any sensible chimpanzee would, beginning with the front one, followed by the second in the row, and so on. When he reached the last tire, he carefully removed it so that no water was lost and carried the tire straight to his aunt, where he placed it upright in front of her. Krom accepted his present without any special acknowledgment and was already scooping water with her hand when Jakie left.

Inasmuch as cooperation is widespread in the animal kingdom, the tendency to assist a member of one's own species is nothing new or original. Yet the precise intention behind it changes as soon as the actor can picture what his assistance means to the other. It is hard to account for Jakie's behavior without assuming that he understood what Krom was after and wished to help her by fetching the tire. Perspective-taking revolutionizes helpful behavior, turning it into cognitive altruism, that is, altruism with the other's interests explicitly in mind.